The present application relates to a fluidic amplifier, particularly a hydraulic linear amplifier for converting a low-energy rotary movement from a control member into a linear setting movement of a piston rod of an operating piston. More particularly, the present invention relates to such a hydraulic linear amplifier, wherein the control member is connected to a threaded spindle whose free end extends into an axial bore of the piston rod and engages in a spindle nut provided in the axial bore, and wherein the pressure fluid charging the operating piston can be controlled via the axial deflection of the control piston of a control valve, which deflection is effected by the control member and the threaded spindle, in order to produce the setting movement of the piston rod, and this setting movement itself can be used to effect a repositioning of the control piston.
In such linear amplifiers, the force is transferred by the piston rod directly to the machine part to be moved without the use of complicated translation mechanisms, which often operate with play in rotary drives. The amplifiers provide precise control of movement and high system rigidity and are suitable for advancing movements as well as for accurate positioning. The drawback in the known amplifiers is their susceptibility to malfunctions. Thus, the amplifier may suffer damage if, for example, a great external force acts on the piston rod when the cylinder is without pressure or if the piston rod cannot overcome the external forces acting on it.